1. Field of the Invention
The present invention relates to well completion equipment, and more specifically to mechanisms for controlling the flow of fluids within a well bore.
2. Description of the Related Art
It is known that after an oil and gas well has been drilled it is completed by lining it with a string of casing that is cemented in place and then perforated adjacent a production zone containing hydrocarbon fluids. The hydrocarbon fluids flow through the casing perforations and into a tubing string positioned within the casing. The tubing string and the casing form an annulus therebetween. It is also known that a well tool that can be selectively opened and closed, commonly known as a "sliding sleeve," may be connected in series with the tubing string to control fluid flow therethrough. The sliding sleeve may be used to control the flow of hydrocarbon fluids from the production zone to the earth's surface, or it can be used to control the flow of various fluids for stimulating or working a well from the earth's surface through the tubing string into the well annulus. Sliding sleeves are generally controlled from the earth's surface by wireline tools, or by other mechanisms known to those of skill in the art. A need has arisen in the industry for a sliding sleeve that may be initially actuated without the use of wireline tools. It has been appreciated that the ability to initially actuate the sliding sleeve without making a trip into the well with wireline tools will result in savings of valuable time and labor. The present invention has been developed in response to this need, and meets this need by providing a sliding sleeve that is initially actuated by annulus pressure instead of by the use of wireline or other tools.